Wait, there are people who genuinely believe this?
Also, them open-sourcing a lot of their tools seems to back that effort up:
Just to name a few.
They really don't stand to gain much by open-sourcing their tools, though, besides developer goodwill, which is something that they sorely needed to remain competitive in today's market.
This is why there is Free software -- free as in choice, not free as in beer -- so users don't get locked in or forced into something other than a simple purchase.
I once interviewed at a young fintech company that proudly said they're Microsoft-first company (ie they use .net stack, azure, outlook and ms teams etc)